Bluetooth® and ZigBee® are open standards for establishing short range peer-to-peer communications, and personal area networks when three or more devices are present. The ZigBee Alliance, which created a suite of ZigBee standards, targeted ZigBee for applications that consume less power than Bluetooth devices. ZigBee personal area networks were also designed to be scalable thereby making it easier for a ZigBee personal area network to link to other ZigBee personal area networks.
Bluetooth, on the other hand, was not designed to be scalable. In Bluetooth personal area networks, a master device must maintain synchronicity between all Bluetooth devices operating in the personal area network. Although technically feasible, it would be difficult to link Bluetooth personal area networks together in a manner that maintains the Bluetooth devices of multiple personal area networks synchronized.